Use of ethoxylated fatty acids as smoothing agents for synthetic and natural fibres

ABSTRACT

A process for treating textile fibers involving contacting the fibers with a composition containing: (a) a compound corresponding to formula I: 
 
R—COO(CH 2 CH 2 O) n H   (I) 
wherein R is a linear or branched, saturated or unsaturated alkyl or alkylene group having from about 5 to 21 carbon atoms and n is a number from about 0.5 to 1.5; (b) optionally, an emulsifier; and (c) optionally, a co-lubricant.

This invention relates firstly to the use of certain ethoxylated fatty acids as smoothing agents for synthetic and natural fibers, to smoothing preparations containing these ethoxylated fatty acids and to a process for smoothing synthetic or natural fibers.

Natural and synthetic staple fibers, which are generally processed for the production of combed slivers, yarns or fabrics, require so-called smoothing preparations which provide for easy processing of the fibers in the process stages of cleaning, opening, mixing, carding, drawing, combing, recombing, spinning, weaving, twisting, embroidering and needling. In the processing steps which precede the actual filament- or fabric-forming processes, such as carding for example, the textile fibers are exposed to severe mechanical stressing, which can result in shortening of the fibers and hence in a reduction in yield.

The reduction in fiber length has a very adverse effect on the quality features of the end product (for example carded sliver, drafter sliver, combed sliver, roving, yarn, twist, woven fabric, knitted fabric, nonwoven). By comparison with undamaged fibers, short fibers lead to a poorer yield and to lower efficiency of the machines involved in the textile manufacturing process, to greater waste, for example during carding and combing/recombing, to unwanted increased hairiness of the yarn, twist, woven or knitted fabric produced, to increased web, roving, yarn and twist breakages, to reduced strength of the yarn, twist, woven fabric, knitted fabric or nonwoven produced, to poorer uniformity of the yarn, twist, woven fabric, knitted fabric or nonwoven produced and to poorer elongation of the yarn, twist, woven fabric, knitted fabric or nonwoven produced.

These problems are of particular significance in the processing of keratinous fibers, especially wool. Wool which is to be processed to combed slivers has to be intensively washed before the actual spinning process in order to remove inorganic soils, such as sand, dust, suit, and organic soils, such as straw, fodder remains, wool and fat. However, the static and dynamic friction conditions of the wool are greatly affected by removal of these soils and particularly by removal of the wool waxes and wool greases, so that subsequent processing of the wool becomes extremely problematical, particularly where intensive fiber/fiber and fiber/metal friction occur. The wool fibers are subjected to severe stressing above all during the carding step where a fiber structure is produced by parallelizing and fine opening. Such stressing often leads to electrostatic charging, to a reduction in the mean staple length of the wool and to increased combing waste in the subsequent processes. In order to counteract electrostatic charging, reductions in staple length and combing waste, the wool has to be treated with so-called combing or smoothing preparations after washing and before carding. These preparations act as lubricants and solve the above-described problems during processing.

The smoothing preparations used—not just for wool—include, for example, olive oil, peanut oil, oleins, fats, fatty acid esters and mineral oils or various kinds in combination with emulsifiers. Although these known combing oils are capable of favorably influencing staple length reductions, combing waste and electrostatic charging, there is still a need for combing oils having an improved effect. For example, the carding rate can be increased by reducing electrostatic charging, product quality can be improved by reducing staple length contraction and economy can be increased by reducing waste.

Numerous smoothing preparations are known from the prior art., cf. for example DE 26 21 881 A1 which discloses a mixture of fatty acid esters and fatty acids containing 14 to 18 carbon atoms and monohydric alcohols containing 1 to 8 carbon atoms, paraffins and fatty acid amidopolyamines as a smoothing preparation. DE 37 06 362 A1 describes dialkyl ether compounds with the same or different, saturated and/or unsaturated hydrocarbon radicals containing 6 to 24 carbon atoms. These dialkyl ether compounds may also be applied to textile fibers of different kinds in the form of smoothing dispersions. It is known from DE 41 14 240 A1 that, besides dialkyl ethers, certain carboxylic acid esters of aliphatic mono-and/or dicarboxylic acids containing 2 to 22 carbon atoms and aliphatic monohydric alcohols containing 1 to 22 carbon atoms and esters of dihydric, trihydric and/or tetrahydric alcohols containing 2 to 22 carbon atoms and aliphatic monocarboxylic acids containing 2 to 22 carbon atoms may also be used as smoothing components in combing oils for the production of combed slivers of wool.

The problem addressed by the present invention was to provide compounds for use in combing oils which would impart high smoothness to both natural and synthetic staple fibers, but at the same time would minimize reductions in staple length, combing waste and electrostatic charging. In addition, the compounds would be easy to wash out and would not contain any resinous, tacky or fiber-damaging constituents. In addition, the smoothing components to be provided by the invention would meet all the other requirements smoothing agents are expected to satisfy. These include resistance to oxidative stress, biodegradability, toxicological compatibility and also good wettability in order to ensure uniform distribution of the preparations over the fibers. However, since the smoothing preparations are only needed for certain process steps, they would have to be easy to wash off completely after use.

It has now been found that the problem stated above can be solved by the use of compounds corresponding to formula (I):

in which R is a linear or branched, saturated or unsaturated alkyl or alkylene group containing 5 to 21 carbon atoms and n is a number of 0.5 to 1.5, as smoothing agents for synthetic and natural fibers.

The compounds of formula (I) used in accordance with the invention are ethoxylated fatty acids known per se. According to the present invention, however, they are distinguished by a low degree of ethoxylation and, at the same time, show a narrow homolog distribution. The production of these compounds is described, for example, in WO 98/25878. According to the teaching of this document, fatty acids are reacted with ethylene oxide in the presence of alkanolamines at elevated temperatures, preferably at 120 to 180° C., and optionally elevated pressure.

Fatty acids in the context of the invention are understood to be aliphatic carboxylic acids corresponding to formula (II):

in which R¹ is an aliphatic, linear or branched alkyl or alkylene group containing 5 to 21 and preferably 11 to 17 carbon atoms and 0 and/or 1, 2 or 3 double bonds. Typical examples are caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid and the technical mixtures thereof obtained, for example, in the pressure hydrolysis of natural fats and oils, in the reduction of aldehydes from Roelen's oxosynthesis or in the dimerization of unsaturated fatty acids. Technical fatty acids containing a total of 12 to 18 carbon atoms such as, for example, coconut oil, palm oil, palm kernel oil or tallow fatty acid or mixtures thereof are preferred.

According to the teaching of WO 98/25878, these fatty acids are reacted with selected catalysts from the group of alkanolamines. Typical examples of alkanolamines suitable as basic catalysts are monoethanolamine, diethanolamine and preferably triethanolamine. The alkanolamines are used in quantities of typically 0.1 to 3% by weight and preferably 0.5 to 1.5% by weight, based on the fatty acids. The ethoxylation itself may be carried out in known manner. The ethoxylated fatty acids of formula (I) used in accordance with the invention are preferably selected so that R in formula (I) stands for an at least monounsaturated alkylene group. In a particularly preferred embodiment, R in formula (I) is a monounsaturated alkylene group containing 17 carbon atoms. The ethoxylated fatty acid is an ethoxylated oleic acid which contains 0.5 to 1.5 mol EO per mol fatty acid. In this case, a compound containing exactly 1 mol EO per mol fatty acid is particularly preferred.

According to the invention, the compounds of formula (I) are preferably used as smoothing agents for keratinous fibers, more particularly for wool. Wool is generally understood to be sheep's wool (WO for short), i.e. the 5 to 30 cm long hairs of the domestic sheep with its various breeds (for example Merino). According to DIN 60001: 1990-10, however, a number of other wools may be included among these quantitatively the most important animal textile fibers, namely the fine under fur of the South American lama (alpaca, vicuna, lama, guanaco wool), the camel, rabbit (angora wool), goat (mohair, cashmere wool) and cattle (yak wool), whereas the coarse outer fur (kemp, long coarse hair) of these animals is known as hair. For reasons of similarity, we also speak of steel wool, metallurgical wool, slag wool, rock wool, basalt wool, glass wool and—previously—of asbestos wool although they have a totally different composition. As a protein fiber, wool (sheep's wool) consists mainly of keratins belonging to the scleroproteins, density of wool: 1.32. The water absorption at 21° C. is 15-17%, the swelling value 40 to 45%. On agitation in boiling water, the wool fibers become matted, i.e. they can be milled and processed to felt. In a dry atmosphere, wool is stable up to ca. 150° C.; decomposition occurs at 250° C. and self-ignition at 590 to 600° C. 24 Amino acids (including the rare lanthionine) joined together as polyamides by peptide bonds, disulfide bridges and (a few) isopeptide bonds are involved in the formation of the long polypeptide chains. Wool contains 10 different keratins which are divided into acidic (type I) and neutral to basic (type II). One type I and one type II keratin form a dimer, 4 dimers form a protofilament, 8 protofilaments form an intermediate filament (IF). In the macrofibrils, the IFs are embedded in a sulfur-rich matrix, the interfilament material. Macrofibrils, cell nucleus residues and cell membrane—they provide the lipid component of wool (ca. 1%)—form the cortex cell. The plate-like cells of the cuticula or scale layer accumulate overlappingly around the cortex or fiber stem. The composition of wool (sheep's wool) corresponds to that described for hair which, in principle, is the same for human hair and animal hair. Technically, wools are classified according to their method of production; the highest quality new wool as wool obtained from live sheep by shearing, dead wool (from dead sheep), slaughterhouse wool or skin wool (from slaughtered animals; known as grease wool, lime wool or enzyme wool, depending on how the skin is treated) and tanner's wool (wool collecting during tanning), see also DIN 60004; 1974-11. By contrast, reclaimed wool is wool recovered from old material. The cleaned wool is processed to combed yarn (low crimp, 170-550 mm long) or to carded yarn (high crimp, 36-250 mm long) according to the length and crimp of the fibers. In addition, wool fibers are classified according to diameter (fineness) with 10 degrees of fineness between AAAA wool (<17 μm) and F wool (>60 μm). Products of “pure wool” must consist of ca. 95% pure sheep's wool whereas products of “wool” must consist of ca. 62% pure sheep's wool. In “wool blends”, the percentage of “wool” must be ca. 51-70%. For subsequent processing, the wool may be subjected to a certain textile finishing treatment such as, for example, milling, carbonizing, chlorination or bleaching (Harris process).

In another preferred embodiment, the compounds of formula (I) are used as smoothing agents for synthetic fibers, preferably polyester fibers. This also includes blends of polyester or other synthetic fibers with natural fibers, preferably keratinous fibers and especially wool. In a particularly preferred embodiment, the compounds of formula (I) are used as smoothing agents for polyester/wool blends which predominantly contain wool, preferably 70 to 80%, the balance to 100% being polyester fibers or other suitable fibers.

The present invention also relates in particular to the use of compounds corresponding to formula (I) as lubricants for the production of combed slivers.

The compounds of formula (I) may be used in various ways in accordance with the present invention. On the one hand, they may be sprayed as such onto or otherwise applied to the fibers to be smoothed. On the other hand, they may be used in the form of ready-made smoothing preparations, which is preferred. Besides the compounds of formula (I) as lubricants, these ready-made smoothing preparations may contain at least one other co-component, namely emulsifiers, in which case the compounds of formula (I) are preferably used in admixture with emulsifiers in a ratio by weight of 99:1 to 30:70. Both individual components and, preferably, mixtures of different emulsifiers may be used. Preferred quantity ratios are in the range from 80:20 to 60:40 (compounds of formula (I):emulsifiers).

Besides the compounds of formula (I), other compounds may be present as lubricants in the ready-made smoothing preparations. In a preferred embodiment, the fatty acid methyl esters disclosed in the above-cited DE 41 14 240 A1 are used in addition to the compounds of formula (I).

The emulsifiers in the smoothing preparations according to the invention may be nonionic, anionic and cationic emulsifiers, for example partial esters of di- and/or triglycerol, such as triglycerol monooleate, alkoxylated, preferably ethoxylated and/or propoxylated, fats, oils, C₈₋₂₂ fatty acids, C₈₋₂₂ fatty alcohols and/or C₈₋₂₂ fatty acid mono and/or diethanolamides, such as optionally ethoxylated oleic acid mono- or diethanolamide, alkoxylated, preferably ethoxylated C₈₋₂₂ fatty acids of which the OH group is replaced by a C₁₋₄ alkoxy group, alkali metal and/or ammonium salts of C₈₋₂₂ alkyl sulfonates, alkali metal and/or ammonium salts of C₈₋₂₂ alkyl sulfosuccinates, such as sodium dioctyl sulfosuccinate. Preferred anionic surfactants are alkyl benzenesulfonates while preferred nonionic emulsifiers are, in particular, fatty alcohol ethoxylates corresponding to formula (III):

where R′″ is a C₈₋₂₂ alkyl group and m is a number of 1 to 10. In addition, it can be of advantage to use mixtures of different emulsifiers. In a preferred embodiment, nonionic emulsifiers are used together with anionic emulsifiers, optionally in combination with other auxiliaries, more particularly pH adjusters.

Fatty acid methyl esters, particularly those of vegetable origin, may advantageously be used as additional lubricants for the ready-made smoothing preparations. Such fatty acid methyl esters are described, for example, in applicants' DE 198 47 497 A1. If fatty acid methyl esters or other suitable lubricants and the compounds of formula (I) are used in combination, it has proved to be of advantage to use them in a quantity ratio of preferably 2:1 to 1:5. Quantity ratios of other smoothing agents to compounds of formula (I) of 1:1 to 1:3 are preferably used. Typical mixtures contain, for example, 20 to 80% by weight of the smoothing agent of formula (I) according to the invention and, as the balance to 100%, the methyl esters disclosed in DE 198 47 497 A1. In another advantageous embodiment, the compounds of formula (I) are present in a quantitative excess over other smoothing agents.

The ready-made smoothing preparations according to the invention contain the emulsifiers in total quantities of 1 to 70% by weight and the compound of formula (I) and optionally other lubricants in quantities of 30 to 99% by weight and optionally other ingredients. In another advantageous embodiment, the ready-made smoothing preparations additionally contain water. This is of course particularly the case when the smoothing preparations are formulated as aqueous emulsions. Other ingredients include in particular—and preferably—antistatic agents, preservatives, pH adjusters and antifoam agents. However, these ingredients may also be separately added during the treatment of wool.

In principle, suitable thickeners, i.e. for increasing the viscosity of the smoothing preparation, are triglycerides, such as the relatively high-viscosity rape oil or polymeric compounds. Winding oils which contain fatty alcohol polymethacrylates to eliminate the tendency of the winding oil to be sprayed off are known from DE 39 36 975. Additives containing carboxyl-free homopolymers and/or copolymers of esters of acrylic acid and/or methacrylic acid with intrinsic viscosities [η] of at least 300 and preferably 800 ml g-1, as measured at 20° C. in tetrahydrofuran, are known from DE-A-39 24 160. The intrinsic viscosities [η] mentioned are normal and are described, for example, in Vollmert “Grundriβ der Makromolekularen Chemie”, Vol. III, pages 55 to 61, Verlag E. Vollmert, Karlsruhe 1982. By virtue of their high intrinsic viscosity, the described additives are capable of improving the drawing and/or adhesion behavior of oils and/or fats.

The lubricants according to the invention are produced in known manner by mixing the ingredients mentioned in any order in the quantities indicated at temperatures of 18 to 25° C.

The present invention relates to a process for smoothing synthetic or natural fibers, in which compounds corresponding to formula (I) are applied to the fibers in quantities of 0.01 to 15% by weight, preferably in quantities of 0.1 to 12% by weight and more particularly in quantities of 0.1 to 5.0% by weight, based on the weight of the fibers. The compounds (I) may be applied by any of the methods known to the expert and are preferably applied by spraying before carding.

The process according to the invention is particularly advantageous where wool fibers are to be smoothed. In this case, too, it has proved to be of advantage to use blends of wool and other fibers, preferably polyester fibers.

The process according to the invention and the use of the ethoxylated fatty acid in accordance with the invention lead on the one hand to improved smoothness of the treated material. This may be utilized to allow the machines involved in subsequent processing, for example carding machines, to operate at maximum speed without any unwanted damage to the substrate. In addition, yield can be increased for the same processing speed. The use of the ethoxylated fatty acids, preferably in combination with animal or vegetable methyl esters, also leads to significantly improved protection of the treated fibers against electrostatic charging in the process steps of carding, drawing, combing, spinning, twisting and needling. This may be utilized, for example, to enable the wool to be dried to a greater extent after washing, resulting in improved removal of vegetable wool impurities during carding without any troublesome electrostatic charging occurring.

Overall, the use of the ethoxylated fatty acid esters according to the invention can lead to an improvement in the economy of the manufacturing process as a whole. It is pointed out in this regard that even a slight improvement in the combed sliver yield, for example of 0.3%, results in an increase of around 30,000 kg per year in the sales volume of combed wool slivers of a medium-sized combed sliver manufacturer (assuming an output of 10,000 t/a).

EXAMPLE

A smoothing preparation according to the invention was produced from the following constituents: oleic acid + 1EO 25% by weight fatty acid methyl ester 50% by weight emulsifier combination based 25% by weight on low-ethoxylated fatty alcohols

This preparation was compared with a smoothing preparation which had the same composition, but only contained vegetable fatty acid methyl esters (mixture of coconut oil/palm kernel oil/palm oil fatty acid methyl ester according to Example 2 of DE 198 47 497).

Both the romaine in % (definition: romaine [%]=combing waste·100/(combing waste+combed sliver) and the electrostatic charging of carded slivers (measuring interval 10 cm in volts) were measured. Electrostatic charging was measured on the web leaving the card using an ELTEX electrofield meter.

The romaine value for the known comparison product was 8.8% and the value for the preparation according to the invention 8.2%. With regard to electrostatic charging of the carded slivers, the value for the comparison product was 110 volts and the value for the preparation according to the invention 77 volts. 

1-20. (canceled)
 21. A process for treating textile fibers comprising contacting the fibers with a composition containing: (a) a compound corresponding to formula I:

wherein R is a linear or branched, saturated or unsaturated alkyl or alkylene group having from about 5 to 21 carbon atoms and n is a number from about 0.5 to 1.5; (b) optionally, an emulsifier; and (c) optionally, a co-lubricant.
 22. The process of claim 21 wherein in formula I R is an at least monounsaturated alkylene group having about 17 carbon atoms.
 23. The process of claim 21 wherein the fibers are selected from the group consisting of wool, polyester, and combinations thereof.
 24. The process of claim 21 wherein (a) and (b) are present in the composition in a ratio by weight of from about 99:1 to 30:70.
 25. The process of claim 21 wherein (a) and (b) are present in the composition in a ratio by weight of from about 80:20 to 60:40.
 26. The process of claim 21 wherein the emulsifier is selected from the group consisting of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and mixtures thereof.
 27. The process of claim 21 wherein (c) and (a) are present in the composition in a ratio by weight of from about 2:1 to 1:5.
 28. The process of claim 21 wherein (c) and (a) are present in the composition in a ratio by weight of from about 1:1 to 1:3.
 29. The process of claim 21 wherein (c) is a fatty acid methyl ester.
 30. The process of claim 21 wherein the fibers are wool.
 31. The process of claim 21 wherein the fibers are polyester.
 32. The process of claim 21 wherein the fibers are combed slivers.
 33. The process of claim 21 wherein the fibers are contacted with the composition in an amount of from about 0.01 to 15% by weight, based on the weight of the fibers.
 34. The process of claim 21 wherein the fibers are contacted with the composition in an amount of from about 0.1 to 12% by weight, based on the weight of the fibers.
 35. The process of claim 21 wherein the fibers are contacted with the composition in an amount of from about 0.1 to 5% by weight, based on the weight of the fibers. 